Torque-biased rotatable member



May 31, 1966 G. w, KNECHT 3,

TORQUEBIASED ROTATABLE MEMBER Filed Jan. 24, 1964 Fig. 1 (a) F13. 10 1 1/2/02 Aer) (PIE/02 Aer) llliill-i-llllllllllll Fig Fig". 5

INVENTOR. ya d/e45 W/fl/Ech r BY www- ATTORNEY United States Patent3,253,482 TORQUE-BIASED RGTATABLE MEMBER George W. Kneeht, Brooklyn,N.Y., assignor to Murray Manufacturing Corporation, Brooklyn, N.Y., acorporation of New York Filed Jan. 24, 1964, Ser. No. 340,055 7 Claims.(Cl. 74-526) This invention relates to a member pivoted within itsperiphery for angular displacement, and is directed to an arrangementfor spring biasing the member relative its pivot.

In numerous applications electrical, mechanical, and electromechanical,it is often found desirable, if not necessary, to spring load apivotedmember to ensure return to a home position subsequent to its beingunlatched from a position to which it had been urged. The member itselfmay act, for example, as a lever, cam, armature, etc., however, thefundamental biasing principle remains the same. The handle mechanism ina circuit breaker is a simple illustration. Generally pivoted near itscenter, the handle is manually urged, activating the internal mechanism,to the set position in which it is latched. Upon being tripped inresponse to an overload in the external circuit, it is desirable thatthe handle return to the off position for indicating the condition ofthe breaker and initiating reset. It is often convenient to bias thehandle itself to effectuate such a result.

Conventional biasing'arrangements take several forms. Since a discussionof two such arrangements, delineating their inherent disadvantages, willserve as an aid in un derstanding the advantages of the presentinvention, such a discussion follows.

FIGS. 1a and 1b illustrate conventional biasing arrangements for a leverand cam, respectively. In FIG. la the lever 2 is mounted upon pivot 1and is biased clockwise by the spring 3. The relative simplicity of suchan assembly lends itself to widespread employment, however, twodisadvantages are immediately apparent. First, an extra lever arm isnecessary for fulcruming the spring, and second, the spring itself liesoutside the structure. The effect in either case is that an area whichcould be employed for another useful purpose is totally lost, withoutresorting to the utilization of a parallel adjacent plane. Since it isoften desirable to maintain the thickness of the apparatus withinminimum limits, the latter solution is not satisfactory.

FIG. lb provides a partial solution. By mounting the spring 6 internallyof the cam 7 and adapting the spring to act in opposition on the cam '7and pivot 5, rotational force is imparted to the cam without resort toan adjacent plane or additional area. This solution, however, is nottotally satisfactory since a poor bearing surface between cam and pivotis created (if only partially), and any angular displacement causes achange in the diameter of the spring and consequently produces apressure inwardly or outwardly (depending upon the direction ofrotation). Moreover, both of the foregoing arrangements exhibit anon-uniformity in the torque exerted on the rotating body. Thisnecessarily arises from the fact that the spring pressure varies,dependent upon the spring distortion or displacement.

Accordingly, it is the object of the present invention to substantiallyuniformly torque bias a rotatable, or pivotal member, and to do so in aminimum area without effecting poor bearing surfaces.

Briefly, the present invention is predicated upon the concept ofinternally torque loading the pivoting member relative the shaft orpivot by means of a rectilinear spring force acting through a variablemoment arm.

The above mentioned and other features and objects of this invention andthe manner of attaining them will "ice become more apparent and theinvention itself will best be understood by reference to the followingdescription of an embodiment of the invention taken in conjunction withthe accompanyingdrawings wherein:

FIGS. 1a and 1b illustrate the conventional torque biasing arrangementspreviously alluded to;

FIGS. 2a and 2b show the torque biasing arrangement, in accordance withthe present invention, in two positions of member rotation;

FIG. 20 shows a side exploded view of the arrangement and memberposition of FIG. 2a; and

FIG. 3 illustrates one embodiment of the described biasing arrangement.

In FIG. 2a the basic member 11 is depicted with-out embellishment. Itwill be appreciated, however, that it may, depending upon is functionalrequisites, constitute a lever, cam, etc., as will be apparent to thoseversed in the art. Further, although the member 11 is shown (in FIG. 2c)as mounted upon a pivot, it may as easily be mounted upon a long shaft,a portion of which takes the shape to be described. Moreover, it willalso be apparent that although for simplicity the outer member isdescribed as that to which rotation is imparted, that element may berigidly maintained and the shaft or pivot angularly displaced.

Member 11 is provided with an irregular opening 12, adapted at the upperportion to embrace the pivot 10 and at the lower portion to provide aspringway for the spring 13. The pivot accepting portion of the openingembraces a sufficient arcuate segment (over to ensure a firm bearinggrip on the pivot; the latter of which has a pieshaped (or sector)section removed to provide a load surface for the upper end of thespring.

Because the spring is laterally displaced with respect to the pivotaxis, the force exerted thereby acts through moment arm M to provide atorque which is a function of this parameter, and the spring pitchdistortion (i.e. the axial distance through which the upper end of thespring is displaced).

FIG. 2b illustrates the effect of rotation upon the spring and momentarm. When the member 11 has undergone approximately 45 of clockwiserotation, the spring 12 has undergone a displacement d. It now actsthrough a new diminished moment arm M. arm and the spring distortionoccur as a result of, and are dependent upon, the lateral displacementof the springway and the size of the removed pivot section. While eachmay be varied from the preferred values shown (in which the displacementis approximately equal to pivot radius, and the segment of pivot removedis approximately 1r/2 radians) within practical limits, it is apparentthat since the torque is a product of the spring force and moment arm,which always vary inversely, the torque itself remains substantiallyconstant within a predetermined angle of displacement.

A novel handle mechanism, such as might be found in a circuitbreakeremploying the inventive concept, is shown in FIG. 3. In rotatingthe handle 17 from the off displacement limit 18 to the on displacement18' a toggle assembly consisting of lower portion 16 of the handle, thepivot 20, and the arm 15, is urged to the left. Simultaneously, thetorque biasing arrangement 10, 12 and 13 assumes the position shown inFIG. 212. When over current persists in the breaker, the toggle releases(not shown) and the handle mechanism by virtue of its internal biasingreturns to the off position, rotating the toggle assembly to the rightpreparatory to reset.

By employing the constant torque bias of the invention the internalmechanism may itself be made more efficient without necessitatingcompensating or over compensating arrangements to obviate the increasedbias ordinarily produced in the on position.

Both the new moment While I have described above the principles of myinvention in connect-ion with specific apparatus, it is to be clearlyunderstood that this description is made only by way of example and notas a limitation to the scope of my invention as set forth in the objectsthereof and in the accompanying claims.

What is claimed is:

1. A rotatable member adapted to be torque biased comprising incombination: a body having a cylindrical bore perpendicularlyintersecting at least one surface, and a springway substantiallyperpendicular to the bore axis and laterally disposed with respectthereto for intersecting at one end of said springway a substantialarcuate segment of said bore; and a cylindrical pivot, having a singlesector cutout, dimensioned for slidable entry into said bore, said bodythereby being angularly displaceable on said pivot.

2. A pivotal torque loaded member comprising in combination; acylindrical pivot having a sector cutout; a body angularly displacea'bleon said pivot having a cylindrical bore perpendicularly intersecting atleast one surface for slidably accepting said pivot and a springwaysubstantially perpendicular to the bore axis and laterally disposed withrespect thereto for intersecting at one end of said springway asubstantial arcua-te segment .of said bore; and a spring disposed insaid springway and bearing upon one surface of said cutout and the otherend of said springway.

3. The pivotal torque loaded member claimed in claim 2 in which thelateral disposition is a distance equivalent to the pivot radius.

4. The pivotal torque loaded member claimed in claim 2 furthercomprising means for limiting the angular displacement of said body.

5. The pivotal torque loaded member claimed in claim 2 in which the saidbore intersecting surface of said body is substantially planar.

6. The pivotal torque loaded member claimed in claim 2 in which saidbody has two parallel planar surfaces, both of which intersect said boreand said springway.

7. A handle mechanism for breaker assemblies comprising in combination acylindrical .pivot, having a sector cutout; a handle body angularlydisplaceable on said pivot having two substantially parallel planarsurfaces, said body having a cylindrical bore perpendicularlyintersecting at least one of said surfaces for slidably accepting saidpivot and a springway substantially perpendicular to the bore axis andlaterally disposed with respect thereto for intersecting at one end ofsaid springway a substantial arcuate segment of said bore; a springdisposed in said springway and bearing upon one surface of said cutoutand the other end of said springway; and means for limiting the angulardisplacement of said handle body.

References Cited by the Examiner UNITED STATES PATENTS 651,706 6/1900Forbes 6429 X 1,061,293 5/1913 Huye 74-592 1,190,888 7/1916 Gordon 200671,457,711 6/1923 Mikkelson. 1,685,310 9/1928 Burrell et al. 74-5282,656,018 10/1953 Bent et al. 74566 .X 2,871,721 2/1959 Abra moska etal. 74566 3,083,932 4/1963 Crowley et al 254 BROUGHTON G. DURHAM,Primary Examiner.

CAROLYN F. GREEN, Assistant Examiner.

7. A HANDLE MECHANISM FOR BREAKER ASSEMBLIES COMPRISING IN COMBINATION A CYLINDRICAL PIVOT, HAVING A SECTOR CUTOUT; A HANDLE BODY ANGULARLY DISPLACEABLE ON SAID PIVOT HAVING TWO SUBSTANTIALLY PARALLEL PLANAR SURFACES, SAID BODY HAVING A CYLINDRICAL BORE PERPENDICULARLY INTERSECTING AT LEAST ONE OF SAID SURFACES FOR SLIDABLY ACCEPTING SAID PIVOT AND A SPRINGWAY SUBSTANTIALLY PERPENDICULAR TO THE BORE AXIS AND LATERALLY DISPOSED WITH RESPECT THEREOF FOR INTERSECTING AT ONE END OF SAID SPRINGWAY SUBSTANTIAL ARCUATE SEGMENT OF SAID BORE; A SPRING DISPOSED IN SAID SPRINGWAY AND BEARING UPON ONE SURFACE OF SAID CUTOUT AND OTHER END OF SAID SPRINGWAY; AND MEANS FOR LIMITING THE ANGULAR DISPLACEMENT OF SAID HANDLE BODY. 